Many applications for wireless communication networks, such as wireless sensors, industrial control and monitoring, intelligent agriculture, asset and inventory tracking, and security, would benefit from a communication protocol that produced an ad-hoc, self-organizing network (i.e. one with a random topology in which the network organization and maintenance occurred without human intervention) that enables each node in the network to be inexpensive and to have low power consumption in all possible connection states. The Cluster Tree Protocol is a protocol for the logical link and network layers for a wireless ad-hoc network designed to meet the above requirements. The Cluster Tree Protocol is described in “Cluster Tree Protocol (ver.0.53)”, by Masahiro Meada, April, 2001, which is hereby incorporated by reference
The protocol uses link-state packets to form either a single cluster network, or a potentially larger cluster tree network. The network is basically self-organizing and supports network redundancy to attain a degree of fault tolerance and self repair. Nodes within the network select a cluster head and form a cluster according to the self-organized manner. In the cluster formation process the cluster head assigns a unique node identifier (ID) to each member node. Self-developed clusters connect to each other using a Designated Device, that is a special node with a high computing ability and large memory space. In many applications the Designated Device is also the gateway between the network and the Internet. The Designated Device assigns a unique cluster ID to each cluster.
Low power consumption is achieved, in part, by each network device having a low duty cycle. For example, a device may be active for only 0.1% of each cycle. However, for asynchronous systems, a low duty cycle makes it difficult for devices to synchronize with one another. For instance, if device A tries to contact device B, there is a high probability that device B is inactive or ‘sleeping’. The problem is compounded by the use of low cost crystal oscillators and on-chip Micro Electro-Mechanical System (MEMS) resonators for timing. The poor frequency performance of these devices increases the need for regular re-synchronization. The Mediation Device Protocol was introduced to enable low duty cycle devices to communicate with each other without requiring a high accuracy synchronization reference, thus overcoming the issue of poor frequency stability. The Mediation Device Protocol is described in detail in “Mediation Device Operation”, Qicai Shi, Ed Callaway, Document IEEE 802.15-01/1880r0, which is hereby incorporated by reference. A mediation device has a relatively long receive period, during which it can record messages in the network. The recorded messages are then played-back to other devices in the network. Hence, the mediation device acts as an “answering machine”.
In order to obtain the benefits of both the Mediation Device Protocol and network layer protocols such as the Cluster Tree Protocol, the protocols must be merged. Consequently, there is an unmet need for a process for merging and using the Mediation Device Protocol with a network layer protocol.